The reviews have been all over the map on Watchmen, and I can see why.
I thought it was very good, but with the exception of Jackie Earle Haley as Rorschach, it didn't approach the greatness of the source material. Watchmen was a visionary comic book, one of the first to be deserving of the term "graphic novel." I agree with the reviewers who noted that it was probably impossible to replicate that vision on the big screen.
The movie begins with a flourish - The Comedian's death scene is brilliantly handled; as are the opening credits which provide backstory for many of the key characters. And importantly, it is in those credits where the movie deviates a bit from the original story, while staying true to its vision. I can understand why the filmmakers chose not to go this route, but had Director Zack Snyder and the screenwriters taken a few more chances like that, it might have pushed the movie into the realm of greatness.
Having said that, this may have been the best possible Watchmen movie that could have been made. Watchmen is subtle in comparison to 300, Snyder's last film, but there are times when it feels almost too reverent. It's a very dark story, but it would have benefited from a touch of humor here and there. The use of music is great, and I especially enjoyed the snippet of a muzaky version of "Everybody Wants to Rule the World" during a scene with Adrian Veidt/Ozymandias. Jackie Earl Haley is the obvious bright light of the cast, although everyone acquits themselves admirably. The actor portraying Ozymandias was a bit lacking in gravitas, but not enough to detract from the proceedings.
I'd hesitate to call it a disappointment - but in the end, Watchmen doesn't quite match the original, and is not in the same league as The Dark Knight or Iron Man.